Connector component for optical fiber, manufacturing method thereof and optical member

ABSTRACT

A connector component for optical fibers has good dimensional accuracy and parallelism. The connector component includes a base material. The base material is provided with at least two holes for inserting and fixing optical fibers therein. The base material is made of quartz glass. Inner components are arranged for forming holes for inserting optical fibers in a die for forming an outer form of the connector component with a dimensional accuracy equal to or less than 2 μm. Slurry is poured into the die, the slurry including quartz powder, a resin binder, a dispersant, water and a curing agent. The poured slurry is cured and heated under vacuum so as to vitrify the cured slurry to obtain the quartz glass.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a connector component for opticalfibers, a manufacturing method therefor and an optical member forarranging optical fibers with good dimensional accuracy and goodparallelism in a connector component for connecting optical fibers andin an optical communication device such as an isolator, a circulator, asplitter, a light guide, a thermochemical switch and an optical switchused in the optical communication field.

2. Description of the Related Art

In the optical communication field, a connector component for opticalfibers such as a single-core ferrule or a two-core ferrule usingzirconia ceramics or glass-ceramic, and a fiber array as shown in FIG. 1in which V-shaped grooves are formed on a board made of glass-ceramic,quartz glass, and silicon are used for setting the optical axis in aconnector for connecting optical fibers, an isolator and a circulator,or a ferrule and a fiber array for optical fibers used for connecting toan AWG waveguide.

However, in the connector component for optical fibers such as a ferrulefor optical communication and a fiber array, when the material of theferrule and the fiber array is zirconia ceramics, in a case where theferrule and fiber array are mechanically stressed, the crystal structureof ceramics is transformed from tetragonal crystal to monocliniccrystal. The phase change causes an increase in the size of theceramics. Thus, the distance between holes of the ferrule and thedistance between the V-shaped grooves of a V-shaped groove type fiberarray change. Accordingly, a high-accuracy optical connection cannot bemaintained for the long term.

Additionally, when the material of the ferrule or the fiber array isdifferent from the material of the optical fibers, the thermal expansioncoefficient of the ferrule or the fiber array differs from the thermalexpansion coefficient of the optical fibers. Therefore, the size of theferrule or fiber array and the size of the optical fibers varydifferently according to the environmental temperature. Thus, bondingsurfaces of the ferrule or fiber array and the optical fibers arestressed. At the same time, there is a possibility that adhesionstrength is deteriorated. Accordingly, such a connector component foroptical fibers is not reliable. Further, when using the V-shaped groovetype fiber array, two to three boards made of quartz are combined so asto fix optical fibers. Thus, more manufacturing processes are required.Additionally, since two to three kinds of costly adhesives are used, theassembling is complex and the cost increases. As a result, diffusion ofoptical communication is prevented.

SUMMARY OF THE INVENTION

It is a general object of the present invention to provide an improvedand useful connector component for optical fibers, manufacturing methodtherefor and an optical member in which the above-mentioned problems areeliminated.

A more specific object of the present invention is to provide aconnector component for optical fibers, manufacturing method thereforand an optical member that can arrange optical fibers with gooddimensional accuracy and good parallelism.

In order to achieve the above-mentioned object, according to one aspectof the present invention, there is provided a connector component foroptical fibers, the connector component including a base materialprovided with at least two holes for inserting and fixing optical fiberstherein, wherein the base material is made of quartz glass (fused silicaglass).

According to the above-mentioned aspect of the present invention, bothoptical fibers and the base material of the connector component foroptical fibers (referred to as “connector component”, hereinafter) aremade of quartz glass. Quartz glass has a small thermal expansioncoefficient. Thus, matching of thermal expansion coefficients of theoptical fibers and the base material is improved. Accordingly, adhesionof the optical fibers and the connector component, such as a ferrule ora fiber array, becomes more reliable. Additionally, compared withV-shaped grooves, surface treatment of bonding surfaces is easier andthe process for polishing, for example, is better. Further, theconnector component is provided with two or more holes for inserting theoptical fibers such that the holes are arranged with a predetermineddistance there between. Therefore, by using the ferrule or the fiberarray structured by a single component, it is possible to arrange andfix a plurality of optical fibers with high accuracy. The holes in theconnector component for optical fibers may be arranged in not only asingle line but also in a plurality of lines. For example, 8 rows×1line, 12 rows×1 line, 40 rows×1 line, 2 rows×2 lines, 4 rows×2 lines, 4rows×4 lines, 8 rows×8 lines, and 10 rows×8 lines.

Additionally, according to another aspect of the present invention,there is provided a manufacturing method for a connector component foroptical fibers, the connector component including a base material madeof quartz glass and provided with at least two holes for inserting andfixing optical fibers, the manufacturing method including the steps of:(a) arranging a plurality of inner components for forming holes forinserting optical fibers in a die for forming an outer form of theconnector component with a dimensional accuracy equal to or less than 2μm; (b) pouring slurry into the die, the slurry including quartz powder,a resin binder, a dispersant, water and a curing agent; (c) curing thepoured slurry; and (d) heating the cured slurry under vacuum so as tovitrify the cured slurry to obtain the quartz glass.

According to the above-mentioned aspect of the present invention, it ispossible to manufacture the connector component for optical fibers withhigh dimensional accuracy.

Additionally, according to another aspect of the present invention, thequartz glass may be high purity quartz glass containing equal to or morethan 99.9% SiO₂, equal to or less than 10 ppm Al₂O₃, equal to or lessthan 1 ppm Li₂O, equal to or less than 10 ppm MgO, equal to or less than10 ppm TiO₂, equal to or less than 10 ppm ZrO₂, equal to or less than 10ppm K₂O, equal to or less than 10 ppm Na₂O, equal to or less than 10 ppmZnO, equal to or less than 10 ppm CaO, and equal to or less than 10 ppmBaO. It is preferable that, by using the above-mentioned high purityquartz glass, the thermal expansion coefficient of the quartz glass ofwhich the connector component is made is controlled to be in a range of0.45˜0.6×10⁻⁷/° C., and the transmission rate of ultraviolet lighthaving wavelength 356 nm is controlled to be equal to or more than 90%.It should be noted that the above-mentioned high purity quartz glass mayinclude another component as long as the component thereof does notcause harm to the optical characteristics of the high purity quartzglass.

Additionally, according to another aspect of the present invention,there is provided an optical member, including: optical fibers; and aconnector component for optical fibers, the connector componentincluding a base material made of quartz glass and provided with two ormore holes for inserting and fixing the optical fibers therein, whereinthe connector component is fixed to ends of the optical fibers by usingepoxy thermosetting type adhesive or ultraviolet curing type adhesive.

According to the above-mentioned aspect of the present invention,exposed strands of optical fibers are inserted into respectivecapillaries (holes), adhesive is filled in between the optical fibersand the capillaries, and a curing light is irradiated to the adhesive.Thereby, the adhesive is solidified and the optical fibers andcapillaries are fixed to each other. Since the irradiated light istransmitted in the capillaries, even when the outer side is covered withan armoring material, it is possible to irradiate the curing lightinside the capillaries from the ends of the capillaries. Further, thecapillaries and the exposed strands of the optical fibers are morepositively adhered and fixed to each other inside the capillaries by theadhesive solidified by the irradiated working light.

According to the above-mentioned aspects of the present invention, whenthe connector component for the optical fibers is combined with opticalfibers, the composition of the connector component and the compositionof the optical fibers are the same, and the thermal expansioncoefficient of the connector component and the thermal expansioncoefficient of the optical fibers are almost the same. Thus, stress tobonded parts does not increase since the stress is due to variation inthe size of the connector component and the optical fibers caused byvariation of environmental temperature. Accordingly, reliability ofadhesion is higher.

The above-mentioned connector component may be more useful since thesizes of fiber arrays have been increasing recently. On the other hand,the optical member and optical component using a ferrule made of quartzand a fiber array made of quartz have advantages in that variouscharacteristics can be obtained almost the same as design targets inoptical designing. As for the various characteristics, there are thepolarized wave dependent property according to a wavelength plate,reduction in loss in AWG (arrayed waveguide grating), dispersionproperty and transmission distance of optical fibers, for example.

Additionally, the optical member combining the connector component andoptical fibers uses light-curing resin as an adhesive. At the same time,in the optical member, capillaries are formed by using a material thatcan transmit working light. Thus, the adhesive is cured by irradiatingthe working light from the ends of the capillaries. Accordingly, besidesthe above-mentioned effects, the capillaries and the optical fibers arefixed to each other.

Therefore, a terminal structure formed by combining the connectorcomponent and optical fibers does not need a burdensome process forsolidifying the adhesive, for example, stopping work on the terminalstructure for a required reaction time so that the adhesive issolidified and performing heat treatment on the terminal structure. Itis possible to simply manage the terminal treatment process of opticalfibers with a predetermined irradiating process. As a result, thebuilding process can be facilitated, efficiency can be improved, andmanufacturing cost can be reduced. Thus, the connector componentaccording to the present invention is suitable for quantity production.

Other objects, features and advantages of the present invention willbecome more apparent from the following detailed description when readin conjunction with the following drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a conventional V-shaped groove array;

FIG. 2A is a front view of a fiber array according to an embodiment ofthe present invention;

FIG. 2B is a longitudinal sectional view of the fiber array in FIG. 2Aaccording to the embodiment of the present invention;

FIG. 3A is a front view of a ferrule according to another embodiment ofthe present invention;

FIG. 3B is a longitudinal sectional view of the ferrule in FIG. 3Aaccording to the embodiment of the present invention;

FIG. 3C is a rear view of the ferrule in FIG. 3A according to theembodiment of the present invention;

FIG. 4 is a schematic diagram showing the structure of a jumper cableusing the fiber array shown in FIGS. 2A and 2B; and

FIG. 5 is a schematic diagram showing the structure of another jumpercable using the ferrule shown in FIGS. 3A, 3B and 3C.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A description will be given of embodiments of the present invention, byreferring to the drawings.

FIG. 2A is a front view of a fiber array 1 according to an embodiment ofthe present invention. FIG. 2B is a cross sectional view of the fiberarray 1.

FIG. 3A is a front view of a ferrule 11 according to another embodimentof the present invention.

FIG. 3B is a cross sectional view of the ferrule 11, and FIG. 3C is arear view of the ferrule 11.

As shown in FIG. 2A, the fiber array 1 is formed by a prismatic basematerial 3 having a plurality of fiber insertion holes 5 therein. Thefiber insertion holes 5 are arranged in a lattice state such as in an 8rows×8 lines arrangement. Additionally, as shown in FIG. 2B, all edgesof the fiber insertion holes on one side of the fiber array 1 arechamfered so as to form surfaces 5 a. In addition, as shown in FIG. 3A,the ferrule 11 is formed by a column-shaped base material 13 having aplurality of fiber insertion holes 15. The fiber insertion holes 15 arearranged in a 2×2 latticed state, for example. As shown in FIGS. 3B and3C, a cone-shaped hollow 13 a is formed on one end of the ferrule 11 sothat the hollow 13 a communicates with the fiber insertion holes 15.

Next, a description will be given of an optical member to which theconnector component for optical fibers according to the above-mentionedembodiments of the present invention is applied. It should be noted thatin this specification, the word “connector component” refers to a fiberarray and a ferrule, and the like.

FIG. 4 is a schematic diagram showing the structure of a jumper cable 21using the above-mentioned fiber array 1. FIG. 5 is a schematic diagramshowing the structure of another jumper cable 31 using theabove-mentioned ferrule 11.

As shown in FIG. 4, the jumper cable 21 is structured by using the fiberarray 1 and optical cables 23. Additionally, as shown in FIG. 5, thejumper cable 31 is structured by using the ferrule 11 and optical fibers33.

The connector components for optical fibers structured as mentionedabove have the same material composition as optical fibers. Thus,thermal expansion coefficients of the connector components and a thermalexpansion coefficient of optical cables are almost the same.Accordingly, when the connector component is combined with the opticalfibers, higher reliability of adhesion is achieved since stresses tobonded parts do not increase. In this case, the stresses are caused byvariations of the sizes of the connector components and optical fibersaccording to the variation of environmental temperature.

In the following, a description will be given of an experiment performedby the inventors of the present invention.

First, quartz powder (average particle diameter: 0.5 μm) of 99.9% puritywas dispersed in alkaline solution with epoxy resin as an organic binderand an organic dispersant. Thus obtained material was put through asieve having 200 meshes, and a hardening agent was added thereto.Thereafter, the material was defoamed by agitation under vacuum so as toobtain slip (slurry). Then, the slip was poured into a die for formingthe outer form of the connector component for optical fibers. Twelveinner components for forming holes for inserting optical fibers werepreviously arranged in the die with a dimensional accuracy equal to orless than 2 μm. When the slip was cured, a formed material was obtained.The formed material was naturally dried for one night. Then, the formedmaterial was tentatively sintered for an hour at 850° C. Thereafter, theformed material was sintered under vacuum atmosphere (equal to or lessthan 10⁻² Torr).

Thus obtained sintered material was in a transparent and colorless glassstate (referred to as. “high purity quartz glass”, hereinafter). Theholes provided in the sintered material were polished using a PC wireand diamond slurry so as to form holes with a predetermined holediameter. Then, the holes were cleaned and a desired fiber array wasobtained. Table 1 shows measured results of a distance between the holesfor inserting the optical fibers of the above-mentioned fiber arrayhaving 12 cores. As shown in Table 1, the holes were arranged with anaccuracy of 250 μm±1 μm with respect to a design target value of 250 μm.TABLE 1 sample distance between holes No. 1-2 2-3 3-4 4-5 5-6 6-7 1250.6 250.2 294.6 249.1 250.3 250.9 2 250.1 250.3 250.9 250.4 249.6250.1 3 250.3 250.2 249.8 249.6 250.3 250.8 4 250.1 249.8 249.6 250.4250.6 250.7 5 249.4 250.6 250.1 250.3 250.0 249.7 sample distancebetween holes No. 7-8 8-9 9-10 10-11 11-12 1 249.1 250.6 250.4 249.5250.5 2 249.1 250.5 249.5 249.9 205.7 3 249.6 249.7 249.3 250.9 250.4 4249.7 249.3 250.1 250.0 250.4 5 249.9 250.6 250.1 250.2 250.7

Additionally, the thermal expansion coefficient of the obtained fiberarray was 0.52×10⁻⁶/° C., which was almost the same thermal expansioncoefficient (0.5×10⁻⁶/° C.) of quartz glass that is the material of theoptical fibers. Further, the fiber array had a 92% transmission rate ofultraviolet light having wavelength 356 nm.

An ultraviolet curing type adhesive was filled in the holes forinserting optical fibers of the fiber array made of glass. Thereafter,single-mode optical fibers were inserted in the respective holes. Theoptical fibers were fixed by irradiating ultraviolet light for 15minutes.

An SC type single-core ferrule was fixed on the other ends of thesingle-mode optical fibers by using a thermosetting adhesive. An opticalfiber cable (optical member) was obtained by optically polishing ends ofthe fiber array and the ends of the SC type single-core ferrule.

Thus obtained optical fiber cable was maintained for 2000 hours under anatmosphere of 85% humidity and 85° C. Then, adhesion strength on thefiber array side was measured. As a result, adhesion strength not lessthan 12 N through 34 N was maintained. Thus, it was confirmed that theconnector component according to the embodiment has high reliability inthe adhesive characteristic.

In the optical member, it is preferable that polarized wave holdingfibers are used for the optical fibers, so that an extinction rate isequal to or greater than 25 dB.

Additionally, in the optical member, it is preferable that each of thethermosetting type adhesive and the ultraviolet curing type adhesive hasequal to or less than 0.2 dB insertion loss, equal to or more than 55 dBreflection loss, and equal to or more than 10 N tensile strength.

The present invention is not limited to the specifically disclosedembodiments, and variations and modifications may be made withoutdeparting from the scope of the present invention.

The present application is based on Japanese priority application No.2002-072710 filed on Mar. 15, 2002, the entire contents of which arehereby incorporated by reference.

1. A connector component for optical fibers, said connector componentcomprising a base material provided with at least two holes forinserting and fixing optical fibers therein, wherein said base materialis made of quartz glass.
 2. The connector component for optical fibersas claimed in claim 1, wherein the quartz glass is high purity quartzglass containing equal to or more than 99.9% SiO₂, equal to or less than10 ppm Al₂O₃, equal to or less than 1 ppm Li₂O, equal to or less than 10ppm MgO, equal to or less than 10 ppm TiO₂, equal to or less than 10 ppmZrO₂, equal to or less than 10 ppm K₂O, equal to or less than 10 ppmNa₂O, equal to or less than 10 ppm ZnO, equal to or less than 10 ppmCaO, and equal to or less than 10 ppm BaO.
 3. The connector componentfor optical fibers as claimed in claim 1, wherein a thermal expansioncoefficient of the quartz glass is within a range of 0.45˜0.6×10⁻⁶/° C.4. The connector component for optical fibers as claimed in claim 1,wherein the quartz glass has equal to or more than 90% transmission ratefor an ultraviolet light having a wavelength of 356 nm.
 5. An opticalmember, comprising: optical fibers; and a connector component foroptical fibers, said connector component including a base material madeof quartz glass and provided with two or more holes for inserting andfixing the optical fibers, wherein said connector component is fixed toends of the optical fibers using epoxy thermosetting type adhesive orultraviolet curing type adhesive.
 6. The optical member as claimed inclaim 5, wherein polarized wave holding fibers are used for the opticalfibers, so that an extinction rate is equal to or greater than 25 dB. 7.The optical member as claimed in claim 5, wherein each of thethermosetting type adhesive and the ultraviolet curing type adhesive hasequal to or less than 0.2 dB insertion loss, equal to or more than 55 dBreflection loss, and equal to or more than 10 N tensile strength.